1. Field of the Invention
The invention relates to a hand-held material-removing tool in general, and more particularly, to a grinding tool for working sheet material.
In recent years, spot welding has been increasingly used in the field of special body repair, because of the pressure on the automobile producers. Advantages provided by spot welding are in particular that a repair can be carried out according to the standards of the respective automobile producer, and this corresponds exactly to the production process of the vehicle. Particular advantages thereby accrue, that e.g. crash behavior of a vehicle corresponds to the original vehicle, even when the vehicle is extensively provided with new material in elements which are load bearing and those which are not.
Furthermore, the problem arises when the new kinds of high strength steel are used that the conventional protective gas welding process lead to embrittlement because of their high heat content, and can thus limit the strength of the whole vehicle structure.
Furthermore, insuring rust protection after the repair can only be guaranteed by using the spot welding process.
However, a prerequisite for satisfactory spot welding it that all surfaces are metallically bare before the welding process.
2. Description of Relevant Art
The grinding process preceding welding is up to now carried out in the workshops with the tools available there. Angle grinders, belt grinders, wire brushes or similar appliances, which remove the primer and paint in the region of the zone of apposition, are in particular used for this purpose. The process of exposing the sheet metal is however very uneven when working freehand, and therefore it cannot be insured that the existing material thickness is maintained, and the material cannot be prevented from being impermissibly weakened by excessive grinding. Furthermore, sparks which arise, particularly in angle grinding, present a danger to the operator.
Since the work appliances mentioned hereinabove were not originally provided for sheet metal grinding, the ease of handling them can also be expected to give rise to problems when material is to be ground away in small corners or angles. The desired uniform exposing of the sheet metal regions to be welded can then only be attained, if at all, by the use of several tools.